Recently, distribution of content information such as images including motion images and still images, music and the like through a communication network has been popularly used. For example, in an image distribution system for distributing image data as content information, an image processing server is prepared on a network and it provides a service of once uploading an image to this image processing server, then automatically converting the uploaded image to the data quantity and the number of colors that can be processed at a portable information processing terminal, and downloading the converted image to the portable information processing terminal so that the converted image can be used at the portable information processing terminal.
Interlocked with such a service, there exists an advertisement information distribution service for distributing advertisement information together with a content to be sent to a portable information processing terminal.
In the conventional advertisement information distribution service, advertisement information of the same content is distributed to all the users. The conventional advertisement information distribution service has a problem that useful information for each user cannot be distributed. Moreover, since the advertisement information of the same content is distributed to all the users, users who receive unwanted advertisement information might take the distribution of this advertisement information as a nuisance and complain to the service provider.
Furthermore, in the conventional advertisement information service, the service provider distributes advertisement information one-sidedly and therefore the information is not shared by users.